{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T07:54:39Z","timestamp":1791273279575,"version":"4.1.0"},"reference-count":59,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2022,3,21]],"date-time":"2022-03-21T00:00:00Z","timestamp":1647820800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nanomaterials"],"abstract":"<jats:p>Two-dimensional (2D) materials and their composites have gained significant importance as the functional layer of various environmental sensors and nanoelectronics owing to their unique properties. This work reports for the first time a highly sensitive, fast, and stable humidity sensor based on the bi-layered active sensing area composed of graphene flower (GF) and poly (vinyl alcohol) PVA thin films for multifunctional applications. The GF\/PVA humidity sensor exhibited stable impedance response over 15 days, for a relative humidity (RH) range of (40\u201390% RH) under ambient operating conditions. The proposed bi-layered humidity sensor also exhibited an ultra-high capacitive sensitivity response of the 29 nF\/%RH at 10 kHz and fast transient response of 2 s and 3.5 s, respectively. Furthermore, the reported sensor also showed a good response towards multi-functional applications such as non-contact skin humidity and mouth breathing detection.<\/jats:p>","DOI":"10.3390\/nano12061026","type":"journal-article","created":{"date-parts":[[2022,3,21]],"date-time":"2022-03-21T21:48:42Z","timestamp":1647899322000},"page":"1026","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":54,"title":["Highly Sensitive and Stable Humidity Sensor Based on the Bi-Layered PVA\/Graphene Flower Composite Film"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8378-2778","authenticated-orcid":false,"given":"Sheik Abdur","family":"Rahman","sequence":"first","affiliation":[{"name":"Faculty of Applied Energy System, Major of Electronic Engineering, Jeju National University, Jeju 63243, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shenawar Ali","family":"Khan","sequence":"additional","affiliation":[{"name":"Faculty of Applied Energy System, Major of Electronic Engineering, Jeju National University, Jeju 63243, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4712-6404","authenticated-orcid":false,"given":"Muhammad Muqeet","family":"Rehman","sequence":"additional","affiliation":[{"name":"Faculty of Applied Energy System, Major of Electronic Engineering, Jeju National University, Jeju 63243, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2747-6618","authenticated-orcid":false,"given":"Woo-Young","family":"Kim","sequence":"additional","affiliation":[{"name":"Faculty of Applied Energy System, Major of Electronic Engineering, Jeju National University, Jeju 63243, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,3,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"525","DOI":"10.1016\/j.apsusc.2019.02.100","article-title":"A novel graphene-based electroluminescent gas sensor for carbon dioxide detection","volume":"479","author":"Seekaew","year":"2019","journal-title":"Appl. Surf. Sci."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"35387","DOI":"10.1039\/C6RA03628G","article-title":"Humidity sensor based on electrospun MEH-PPV:PVP microstructured composite","volume":"6","author":"Azmer","year":"2016","journal-title":"RSC Adv."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"2021","DOI":"10.1007\/s12274-016-1389-y","article-title":"Transparent, stretchable, and rapid-response humidity sensor for body-attachable wearable electronics","volume":"10","author":"Trung","year":"2017","journal-title":"Nano Res."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1702076","DOI":"10.1002\/adma.201702076","article-title":"Highly Sensitive MoS2 Humidity Sensors Array for Noncontact Sensation","volume":"29","author":"Zhao","year":"2017","journal-title":"Adv. Mater."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1600404","DOI":"10.1002\/advs.201600404","article-title":"Porous Ionic Membrane Based Flexible Humidity Sensor and its Multifunctional Applications","volume":"4","author":"Li","year":"2017","journal-title":"Adv. Sci."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"595","DOI":"10.1039\/C8MH01160E","article-title":"An intrinsically stretchable humidity sensor based on anti-drying, self-healing and transparent organohydrogels","volume":"6","author":"Wu","year":"2019","journal-title":"Mater. Horiz."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"471","DOI":"10.1016\/j.snb.2015.12.027","article-title":"Remarkable humidity-responsive sensor based on poly (N,N-diethylaminoethyl methacrylate)-b-polystyrene block copolymers","volume":"226","author":"Geng","year":"2016","journal-title":"Sens. Actuators B Chem."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Sappat, A., Wisitsoraat, A., Sriprachuabwong, C., Jaruwongrungsee, K., Lomas, T., and Tuantranont, A. (2011, January 17\u201319). Humidity sensor based on piezoresistive microcantilever with inkjet printed PEDOT\/PSS sensing layers. Proceedings of the ECTI-CON 2011\u20148th Electrical Engineering\/Electronics, Computer, Telecommunications and Information Technology (ECTI) Association of Thailand\u2014Conference 2011, Khon Kaen, Thailand.","DOI":"10.1109\/ECTICON.2011.5947764"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"650509","DOI":"10.1155\/2009\/650509","article-title":"Influence of MWCNTs Doping on the Structure and Properties of PEDOT:PSS Films","volume":"2009","author":"Li","year":"2009","journal-title":"Int. J. Photoenergy"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1645","DOI":"10.1039\/c0an00133c","article-title":"Silver nanoparticle polymer composite based humidity sensor","volume":"135","author":"Power","year":"2010","journal-title":"Analyst"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"194","DOI":"10.1016\/j.sna.2010.10.018","article-title":"Flexible humidity and temperature sensor based on cellulose\u2013polypyrrole nanocomposite","volume":"165","author":"Mahadeva","year":"2011","journal-title":"Sens. Actuators A Phys."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"658","DOI":"10.1016\/j.snb.2013.11.004","article-title":"A dew sensor based on modified carbon black and polyvinyl alcohol composites","volume":"192","author":"Jiang","year":"2013","journal-title":"Sens. Actuators B Chem."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"267","DOI":"10.3390\/s7030267","article-title":"Gas Sensors Based on Conducting Polymers","volume":"7","author":"Bai","year":"2007","journal-title":"Sensors"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"274","DOI":"10.1166\/sl.2005.045","article-title":"Humidity Sensors: A Review of Materials and Mechanisms","volume":"3","author":"Chen","year":"2005","journal-title":"Sens. Lett."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"120","DOI":"10.1016\/j.snb.2009.11.041","article-title":"Novel resistive-type humidity sensor based on multiwall carbon nanotube\/polyimide composite films","volume":"145","author":"Yoo","year":"2010","journal-title":"Sens. Actuators B Chem."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"4103","DOI":"10.1038\/srep04103","article-title":"Ultrafast response humidity sensor using supramolecular nanofibre and its application in monitoring breath humidity and flow","volume":"4","author":"Mogera","year":"2014","journal-title":"Sci. Rep."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"11166","DOI":"10.1021\/nn404889b","article-title":"Ultrafast Graphene Oxide Humidity Sensors","volume":"7","author":"Borini","year":"2013","journal-title":"ACS Nano"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"478","DOI":"10.1039\/C7TA08775F","article-title":"3D superhydrophobic reduced graphene oxide for activated NO2 sensing with enhanced immunity to humidity","volume":"6","author":"Wu","year":"2018","journal-title":"J. Mater. Chem. A"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"19097","DOI":"10.1021\/acsami.8b03524","article-title":"Highly Stretchable and Transparent Thermistor Based on Self-Healing Double Network Hydrogel","volume":"10","author":"Wu","year":"2018","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"10078","DOI":"10.1039\/c3ta11774j","article-title":"Graphene-based gas sensors","volume":"1","author":"Yuan","year":"2013","journal-title":"J. Mater. Chem. A"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"5573","DOI":"10.1039\/c3ta13823b","article-title":"Nanocarbon-based gas sensors: Progress and challenges","volume":"2","author":"Mao","year":"2014","journal-title":"J. Mater. Chem. A"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"6739","DOI":"10.1021\/nn500504s","article-title":"Poly(vinyl alcohol) reinforced and toughened with poly(dopamine)-treated graphene oxide, and its use for humidity sensing","volume":"8","author":"Hwang","year":"2014","journal-title":"ACS Nano"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Rehman, H.M.M.U., Rehman, M.M., Saqib, M., Khan, S.A., Khan, M., Yang, Y., Kim, S., Rahman, S.A., and Kim, W.-Y. (2021). Highly Efficient and Wide Range Humidity Response of Biocompatible Egg White Thin Film. Nanomaterials, 11.","DOI":"10.3390\/nano11071815"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"451","DOI":"10.1016\/j.snb.2010.12.046","article-title":"Epitaxially grown graphene based gas sensors for ultra sensitive NO2 detection","volume":"155","author":"Pearce","year":"2011","journal-title":"Sens. Actuators B Chem."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"130371","DOI":"10.1016\/j.snb.2021.130371","article-title":"All range highly linear and sensitive humidity sensor based on 2D material TiSi2 for real-time monitoring","volume":"345","author":"Shaukat","year":"2021","journal-title":"Sens. Actuators B Chem."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1746","DOI":"10.1021\/jz300358t","article-title":"Graphene-Based Chemical Sensors","volume":"3","author":"Yavari","year":"2012","journal-title":"J. Phys. Chem. Lett."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"188","DOI":"10.1016\/j.colsurfb.2013.05.022","article-title":"Graphene-based materials biocompatibility: A review","volume":"111","author":"Pinto","year":"2013","journal-title":"Colloids Surf. B Biointerfaces"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"54","DOI":"10.1016\/j.sna.2015.05.007","article-title":"Opto-electronic humidity sensor: A review","volume":"233","author":"Sikarwar","year":"2015","journal-title":"Sens. Actuators A Phys."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"47","DOI":"10.1080\/15421406.2020.1743437","article-title":"Temperature-sensing behavior of poly(vinylidene fluoride-trifluoroethylene) film","volume":"706","author":"Khan","year":"2020","journal-title":"Mol. Cryst. Liq. Cryst."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"037566","DOI":"10.1149\/1945-7111\/ab697c","article-title":"Review\u2014The Development of Wearable Polymer-Based Sensors: Perspectives","volume":"167","author":"Harito","year":"2020","journal-title":"J. Electrochem. Soc."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"eaap9841","DOI":"10.1126\/sciadv.aap9841","article-title":"Soft, smart contact lenses with integrations of wireless circuits, glucose sensors, and displays","volume":"4","author":"Park","year":"2018","journal-title":"Sci. Adv."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1700310","DOI":"10.1002\/admt.201700310","article-title":"Recent Progress in Wearable Fully Textile Chemical Sensors","volume":"3","author":"Tessarolo","year":"2018","journal-title":"Adv. Mater. Technol."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"14997","DOI":"10.1038\/ncomms14997","article-title":"Wearable smart sensor systems integrated on soft contact lenses for wireless ocular diagnostics","volume":"8","author":"Kim","year":"2017","journal-title":"Nat. Commun."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"562","DOI":"10.1002\/elan.201400537","article-title":"Tattoo-Based Wearable Electrochemical Devices: A Review","volume":"27","author":"Bandodkar","year":"2015","journal-title":"Electroanalysis"},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Martadi, S., Sulthoni, M.A., Wiranto, G., Surawijaya, A., and Herminda, I.D.P. (2019, January 8\u20139). Design and fabrication of PVA-based relative humidity sensors using thick film technology. Proceedings of the 2019 International Symposium on Electronics and Smart Devices (ISESD), Badung, Indonesia.","DOI":"10.1109\/ISESD.2019.8909519"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"149","DOI":"10.2528\/PIERB13061716","article-title":"Polyvinyl-Alcohol (PVA)-Based rf humidity sensor in microwave frequency","volume":"54","author":"Amin","year":"2013","journal-title":"Prog. Electromagn. Res."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"8143","DOI":"10.3390\/s110808143","article-title":"Fabrication and Characterization of Polyaniline\/PVA Humidity Microsensors","volume":"11","author":"Yang","year":"2011","journal-title":"Sensors"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"387","DOI":"10.1007\/s00604-021-04945-4","article-title":"TiO2\/MXene-PVA\/GO hydrogel-based electrochemical sensor for neurological disorder screening via urinary norepinephrine detection","volume":"188","author":"Boobphahom","year":"2021","journal-title":"Mikrochim. Acta"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"2000426","DOI":"10.1002\/admt.202000426","article-title":"Biocompatible and Highly Stretchable PVA\/AgNWs Hydrogel Strain Sensors for Human Motion Detection","volume":"5","author":"Azadi","year":"2020","journal-title":"Adv. Mater. Technol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1016\/j.bios.2018.05.038","article-title":"Wearable humidity sensor based on porous graphene network for respiration monitoring","volume":"116","author":"Pang","year":"2018","journal-title":"Biosens. Bioelectron."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"240","DOI":"10.1016\/S0925-4005(98)00134-8","article-title":"Humidity sensors using polyvinyl alcohol mixed with electrolytes","volume":"49","author":"Yang","year":"1998","journal-title":"Sens. Actuators B Chem."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"128934","DOI":"10.1016\/j.snb.2020.128934","article-title":"Application of self-heating graphene reinforced polyvinyl alcohol nanowires to high-sensitivity humidity detection","volume":"327","author":"Chen","year":"2021","journal-title":"Sens. Actuators B Chem."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Khan, S.A., Saqib, M., Rehman, M.M., Mutee Ur Rehman, H.M., Rahman, S.A., Yang, Y., Kim, S., and Kim, W.Y. (2021). A full-range flexible and printed humidity sensor based on a solution-processed p(Vdf-trfe)\/graphene-flower composite. Nanomaterials, 11.","DOI":"10.3390\/nano11081915"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"105102","DOI":"10.7567\/APEX.6.105102","article-title":"X-ray Tube Using a Graphene Flower Cloth Field Emission Cathode","volume":"6","author":"Iwai","year":"2013","journal-title":"Appl. Phys. Express"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"04EC11","DOI":"10.7567\/JJAP.55.04EC11","article-title":"Miniaturized ascorbic acid fuel cells with flexible electrodes made of graphene-coated carbon fiber cloth","volume":"55","author":"Hoshi","year":"2016","journal-title":"Jpn. J. Appl. Phys."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"02BE05","DOI":"10.7567\/JJAP.55.02BE05","article-title":"Graphene-coated carbon fiber cloth for flexible electrodes of glucose fuel cells","volume":"55","author":"Hoshi","year":"2016","journal-title":"Jpn. J. Appl. Phys."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"127693","DOI":"10.1016\/j.snb.2020.127693","article-title":"Surface acoustic wave humidity sensor based on three-dimensional architecture graphene\/PVA\/SiO2 and its application for respiration monitoring","volume":"308","author":"Su","year":"2020","journal-title":"Sens. Actuators B Chem."},{"key":"ref_48","first-page":"384","article-title":"Humidity-Insensitive NO2 Sensors Based on SnO2\/rGO Composites","volume":"9","author":"Wang","year":"2021","journal-title":"Front. Chem."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"494","DOI":"10.1016\/j.micromeso.2016.01.031","article-title":"Liquid exfoliation of black phosphorus nanosheets and its application as humidity sensor","volume":"225","author":"Late","year":"2016","journal-title":"Microporous Mesoporous Mater."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"2311","DOI":"10.1039\/C9NA00179D","article-title":"A highly sensitive printed humidity sensor based on a functionalized MWCNT\/HEC composite for flexible electronics application","volume":"1","author":"Turkani","year":"2019","journal-title":"Nanoscale Adv."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"131507","DOI":"10.1016\/j.snb.2022.131507","article-title":"Two dimensional Zirconium diselenide based humidity sensor for flexible electronics","volume":"358","author":"Shaukat","year":"2022","journal-title":"Sens. Actuators B Chem."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"2127","DOI":"10.1109\/LPT.2015.2454271","article-title":"Optical Fiber Fabry\u2013Perot Humidity Sensor Based on Porous Al2O3 Film","volume":"27","author":"Huang","year":"2015","journal-title":"IEEE Photonics Technol. Lett."},{"key":"ref_53","doi-asserted-by":"crossref","unstructured":"Arunachalam, S., Gupta, A.A., Izquierdo, R., and Nabki, F. (2018). Suspended Carbon Nanotubes for Humidity Sensing. Sensors, 18.","DOI":"10.3390\/s18051655"},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"5806","DOI":"10.1007\/s10854-018-8552-z","article-title":"Wide range and stable ink-jet printed humidity sensor based on graphene and zinc oxide nanocomposite","volume":"29","author":"Hassan","year":"2018","journal-title":"J. Mater. Sci. Mater. Electron."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"12592","DOI":"10.1109\/JSEN.2020.3002951","article-title":"Printed Carbon Nanotubes-Based Flexible Resistive Humidity Sensor","volume":"20","author":"Zhang","year":"2020","journal-title":"IEEE Sens. J."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"28002","DOI":"10.1021\/acsami.7b05181","article-title":"Drawn on Paper: A Reproducible Humidity Sensitive Device by Handwriting","volume":"9","author":"Zhao","year":"2017","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"133751","DOI":"10.1016\/j.cej.2021.133751","article-title":"Rapid, highly sensitive, and highly repeatable printed porous paper humidity sensor","volume":"433","author":"Zhang","year":"2022","journal-title":"Chem. Eng. J."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"112072","DOI":"10.1016\/j.sna.2020.112072","article-title":"All printed full range humidity sensor based on Fe2O3","volume":"311","author":"Khan","year":"2020","journal-title":"Sens. Actuators A Phys."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"21522","DOI":"10.1039\/C9NR06751E","article-title":"A fully inkjet-printed transparent humidity sensor based on a Ti3C2\/Ag hybrid for touchless sensing of finger motion","volume":"11","author":"Li","year":"2019","journal-title":"Nanoscale"}],"container-title":["Nanomaterials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-4991\/12\/6\/1026\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T22:40:24Z","timestamp":1760136024000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-4991\/12\/6\/1026"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,3,21]]},"references-count":59,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2022,3]]}},"alternative-id":["nano12061026"],"URL":"https:\/\/doi.org\/10.3390\/nano12061026","relation":{},"ISSN":["2079-4991"],"issn-type":[{"value":"2079-4991","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,3,21]]}}}